Wall with sound absorbing material positioned behind an array of sound reflectors



Feb. 5, 1952 E T, FlsK ETAL 2,584,797

WALL W'ITH SOUND ABSORBING MATERIAL POSITIONED l BEHIND AN ARRAY OF' SOUND REFLECTORS Flled Dec 20, 1946 lll-ITT.

Patented Feb. 5, 1952 WALL WITH SOUND ABSORBING MATERIAL POSITIONED BEHIND AN ARRAY OF SOUND REFLECTORS Ernest Thomas Fisk, London, and Alexander Wood, Cambridge, England, assignors to Electric & Musical Industries Limited, Hayes, England, a company of Great Britain Application December 20, 1946, Serial No. 717,376 In Great Britain November 24, 1945 Section 1, Public Law 690, August 8, 1946 Patent expires November 24, 1965 2 Claims. l f

This invention relates to sound recording or broadcasting studios, concert halls, music rooms or the like, hereinafter referred to as studios It is found with such studios that the frequency range over which substantially faithful reproduction can be obtained has an upper limit of the order of 5000 cycles per second, owing to the natural sound absorbing properties of the studio walls or ceiling or due to the provision of reflectors according to one embodiment ofI the invention in which the reflectors comprise metal or glass discs, and

Figures 2 and 3 illustrate other embodiments of the invention in which the reflectors comprise strips of Wood or other suitable material.

As shown in Figure 1 the reflectors l are in the form of discs made of polished glass or metal, a large number of said reflectors being provided sound absorbing material which serves to prethe dimensions of the particular reflectors being vent reflections occurring, and consequently the so chosen that together they serve to cause subsound is lacking in the higher frequency restantially uniform reflection over the desired, sponse, if it is desired that substantially falthfrequency range to be augmented. Alternaful reproduction be obtained extending up to tively selective reflectors may be employed so as about 15,000 cycles per second, to augment some frequencies to a greater extent The object of the present invention is to iinthan other frequencies. In one example a large prove the frequency response characteristics of number of glass discs of approximately 1A in studios with a view to obtaining a more faithful thickness may be employed, said discs having reproduction extending over a wider frequency diameters varying from 6" to 18". A disc of range than heretofore. such form of 15" in diameter affords a strong re- According to the present invention, in a studio Flection at 8,000 cycles per second and by suitsound reflectors are provided so disposed and of ably choosing the sizes of said reflectors and such dimensions as to cause reflection of sound their distribution throughout the studio the freover a range of frequencies to be augmented, quency response of the studio above 5,000 cycles said reflectors causing, however, only negligible per second can be augmented up to the desired reflection at lower frequencies. maximum of 15,000 cycles per second.

Said refleCOrS aCCOldfle to one embodiment Said reflectors may be applied to the existing Of the IlVeIltOn may COIIIDIS@ pOUShed metal Or walls and/or ceiling of a studio and they may be glass discs or the like, the diameters 0r equivalent so oriented as to cause reflection of the sound dmenlSOIlhOf vlllh ae ldalgcmlaire Wflthdte 3U in a desired direction such as towards a micro- Wave eng 0 e S011!! W 1C l 1S @Sll 0 phone. Furthermore, if desired, the distance of reflect 01' aCCOrdIlg to another embodiment of said reiiectors from the microphone and their the invention said reflectors may comprise strips distribution may be S0 Chosen as to afford of wood or other suitable material, the Width of muiiiipie reiiections so as to increase the reverthe strips being chosen so as to cause the desired beiation time ai the upper frequenciesreflection of the upper frequencies. Said reflec- In Figure 1 the discs are shown as being artors are adapted t0 cau-Se the up'pe" frequencles ranged in vertical rows, the discs in one row bet0 be aug'umentedby pure 1 `eect1fm rather than ing of a different size from the discs in another 151/ hsmg the dmenstlonts 0f fljldlrefleftors S0 row. This however, is not essential since the ci; ey are resonan a paldcu ar ffequen' 40 discs can be arranged in any desired manner.

Preferably the reflection co-eflicient of said relndlscdaespld rrim the Studio dwells or flectors is higher than the reflection co-eflicient .t a s ppo e .or supen m ami of the studio walls or ceiling and preferably sul a e ngld Tanner' Wlgh disc? 0 1 glass 01 suitable sound absorbing material is placed bemetal the reevtlon co'emcent 7111.111 general hind Said reectors to absorb 10W frequency be better than therefiection co-eficient of the components which pass the reflectors S0 as to en- Studio walls or ceiling and hence the latter will sure that the higher frequency components are absorb the 10W frequency components Whlch pass reflected to a, greater degree than the 10W frethe reflectors, although if desired suitable sound quency components. abfsorbing materialzsuch as felt, indicated by the In order that the said invention may be clearly le eleIlCe numeral may be dSDOSed behind the understood and readily carried into effect it will discs so ensuring that the higher frequency com- ;ilow be more fullyddescribed with releference to ponents are reflected to a greater degree than e accompanying rawings, in whic the ow frequency components. In this way the Figure l illustrates diagrammatically sound greater relative absorption of the higher frequency components which normally occurs in the absence of the invention is avoided.

Instead of employing reflectors of disc form, reflectors of other shapes may be employed. Furthermore, said reflectors may be mounted on panels or other suitable structures so as to form reflecting units, which units may be mounted on suitable castors whereby they can be readily distributed in desired positions throughout the studio.

Figures 2 and 3 of the drawings illustrate further embodiments of the invention in which reiiectors are in the form of strips 3 of Wood or other suitable material, the width of the various strips being chosen so as to cause the desired reflection of the upper frequencies. In the case, for example, where it is desired to extend the frequency range over which a substantially faithful reproduction can be obtained up to about 15,000 cycles per second, strips of wood 1" in thickness and 2, 4 and 6" wide can be employed, suitably secured to the walls and/or ceiling of astudio. Said strips 3 can be arranged in effect like panels at various parts oi the studio walls and ceiling and preferably each panel cornprises two sets of strips as shown in Figures 2 and 3, one set of strips being arranged behind the other and with the longitudinal axes of the strips disposed at right-angles to one another as shown in Figure 2 with one set of strips vertical and the other set horizontal or they .may be arranged as shown in Figure 3. The front set of strips and the rear set of strips are arranged in contact with one another and may be secured together where they overlap. Said strips may be held in position on the walls or ceiling by securing them to asupporting framework 4 (Figure 3) or said strips may be directly secured to the walls or ceiling or the studio, said strips being disposed about three to six inches from the walls and ceiling. 1i" the strips 3 are made of wood, such as deal, although other materials can, of course, be employed, the reflection coefficient of such material may not be suniciently high to cause reflection to the desired extent, in which case suitable sound absorbing material is placed behind said strips, said sound absorbing material being indicated at 5 in Figures 2 and 3, so as to absorb low frequency components which pass the strips, thus ensuring that the higher frequency components are reflected to a greater degree than the low frequency components as aforesaid.

The strips of different width need not be arranged in any particular order; the strips are, however, suitably spaced apart from one another with the narrow and Wider strips spaced with a constant spacing or with a varying spacing as may be found desirable.

Although the invention is particularly applicable to sound recording or broadcasting studios, it may also be applied to concert halls and the like to improve the quality of the sound heard by listeners therein.

We claim:

1. A room having walls adjacent which an array of sound wave reflectors is provided, said array comprising a plurality of reflecting surface elements of varying sizes oriented and arranged in a plurality of rows adjacent the walls of said room, the adjacent rows being spaced from each other and in non-contiguous relation, each row containing reflecting elements of only a single size, the dimensions of said reflecting elements being large compared to the wavelength of the particular sound waves which are desired to be reflected, the reflecting elements al1 being spaced from the adjacent wall of the room, and sound absorbing material positioned behind said reiiecting elements, between such elements and the adjacent wall of the room.

2. A room in accordance with claim 1, wherein the reflecting elements are disc elements on the order of six inches to eighteen inches in diameter to reflect sound wave frequencies in the range of ve thousand to fifteen thousand cycles per second.

ERNEST THOMAS FISK. ALEXANDER WOOD.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,675,102 Holland June 26, 1928 1,825,465 McDonald Sept. 29, 1931 1,975,604 Hanson Oct. 2, 1934 2,224,651 Jacobs Dec. l0, 1940 FOREIGN PATENTS Number Country Date 650,313 France Jan. 8, 1929 337,900 Great Britain Nov. 13, 1930 495,755 Great Britain Nov. 16, 1938 

